Libby Lenton's dream of seven gold medals was ended by student Caitlin McClatchey, who was the first of two Scottish gold medallists on the opening day of the Commonwealth Games on Thursday.

Australian euphoria from a well-received opening ceremony the night before was dampened by a drugs controversy, but the hosts still topped the medal count with three of the 11 gold medals contested.

Indian weightlifter Kunjarani Nameirakpam claimed the honour of winning the first gold medal of the 18th Games in the women's 48 kilogram division with a Games record final lift.

But McClatchey scored the first big upset when she stunned Lenton to win the women's 200 metres freestyle, swimming an astonishing last 50 metres.

Lenton had been on world record pace but faded as McClatchey set a Games record of one minute 57.25 seconds.

"It was a bit of a shock but it's good," said McClatchey, the 400m bronze medallist at the 2005 world championships.

Lenton touched 0.26 behind for silver, with Melanie Marshall third.

"It's impossible, so it's a bit of pressure off," Lenton said of her unlikely seven-gold target.

David Carry made it a stunning night for Scotland when he triumphed in a weakened men's 400m freestyle, reeling in Welshman David Davies just before the final turn to win in 3:48.17.

Canadian Andrew Hurd beat Davies for silver while Craig Stevens, the man who replaced an ailing Ian Thorpe, was fourth.

Australia won its first and only pool gold medal when teenager Stephanie Rice upset pre-race favourite Brooke Hanson in the women's 200m individual medley, Lara Carroll ensuring an Australian podium sweep.

New Zealander Moss Burmester's team mates greeted his men's 200m butterfly victory with a haka war dance. Burmester set a new Games record of 1:56.64 in beating Australian Travis Nederpelt.

Australia again had to settle for silver as South Africans Roland Schoeman, Lyndon Ferns, Johannes Zandberg and Ryk Neethling won the men's 4x100m freestyle.

FIRST GOLD

Olympic champion and world record holder Anna Meares claimed Australia's first gold medal of the competition when she won the women's 500 metres time-trial in 34.326 seconds.

Meares's time bettered a short-lived Games record set earlier by eventual silver medallist Victoria Pendleton of England. The Australian's sister Anna claimed bronze.

Ben Kersten made it two Australian velodrome golds with a scorching win in the men's 1km time-trial. Paul Manning opened England's account by winning the 4000m individual pursuit, beating team mate and world team pursuit champion Rob Hayles.

A drug cloud hung over the hosts as Australian Sports Minister Rod Kemp confirmed that unidentified tablets had been found along with syringes and vials in rooms occupied by home weightlifters at the Australian Institute of Sport in Canberra.

The results of tests will likely be known on Friday, with Australian chef-de-mission John Devitt warning against directly linking Australia's weightlifters to the discovery until those results were in.

Organisers have declared that the 4,500 athletes competing in Melbourne could expect one of the toughest anti-doping blitzes ever, with almost one in four to be tested.

But even then Devitt had to admonish marathon runner Scott Westcott for saying he would probably take a caffeine tablet before Sunday's race. While not banned, the use of caffeine is still viewed with suspicion by the World Anti-Doping Agency.